After consideration of the evidence of record, the presiding officer may dismiss the petition in whole or in part, and enter an order to that effect. If he does not dismiss it in whole, he will issue and serve on the parties an order approving the rate(s) or change in rate(s) determined by the presiding officer to be just and reasonable. The order will include a statement of findings and conclusions as well as the reasons therefor on all material issues of fact, law and discretion.
Ill. Admin. Code tit. 92, § 446.504